In one conventional mechanism, water-tightness is obtained in a watch case by engaging the inner case body directly with the outer case body and pressing a gasket between the inner case body and a glass. This conventional mechanism, however, has a complicated manufacture and unstable water-tightness.
Another known structure, as will be described in detail hereinafter, is such that water-tightness is obtained by engaging a pin fixed to a leaf spring into a groove provided on an outer case body and pressing a gasket between the inner case body and a glass. In this structure, the fixation of a pin to a leaf spring makes it difficult to obtain accuracy in manufacture and, furthermore, the water-tightness is unstable. Moreover, since it is necessary to make the leaf spring large in width for facilitating the fixing of the pin to the leaf spring, the thickness of the inner case body must be large. Therefore, the outer case body must be very thick, which spoils the outward appearance thereof.